I spoke with Diana, a serial entrepreneur who also founded Savings.com, to find out what those surprising secrets were and what pre-retirees should do now if they want to join the club. I confess that the results did, indeed, surprise me. (You can pose your own questions at The Retiree Next Door one-hour tweet jam Tuesday November 18 at 11 a.m. PT; 2 p.m. ET; I’ll be participating.)

Diana: We did a survey of boomers four months ago and found that half of boomers were not satisfied with their finances and a third had no plan. We thought that was a recipe for disaster for a large body of Americans, so we said: ‘Let’s reach some successful retirees and see how they are doing and how did they get there so we can help boomers approaching retirement.’

What did the successful retirees have in common?

They’re living within their means and they had a savings plan for retirement. About a quarter of them calculated how much they’d need to retire when they were in their 40s; another 21 percent did it in their 50s.

44 percent said they were comfortably retired with less than $500,000 in assets. That surprised me quite a bit. I’m in my 40s and that wouldn’t cut it for me.

What does this tell you?

It hits on one of the ingredients in the root of what I uncovered through the survey, which is that successful does not mean ‘I’ve got gobs of money and houses all over the place and cars.’ People who came to terms with what they wanted out of life and managed to figure how to budget and live within that were happily retired.

Are the successful retirees frugal?

No. They’ve been prudent, not frugal. Only 35 percent call themselves frugal; the rest said they spend enough to live comfortably. And 67 percent live on less than a $100,000 a year; 23 percent are in the 25 to 50 grand bucket.

The key is that two-thirds of them have been on some kind of monthly budget and stuck to it.

About 62 percent consulted advisers, at least some of the time, through their career to make investment decisions.

Was having a financial adviser useful for them?

Without a doubt. Engaging an adviser made them more likely to have a budget and to live within it.

What investment mistakes did the successful retirees regret making?

One big mistake they made was getting into the stock market too late or getting out of it too late. They tried to rifle-shot the market. And the other mistake they made was making bad real estate bets.

What keeps them up at night?

The fear of outliving their savings and incurring substantial health care costs. And twenty five percent are concerned about maintaining their standard of living. They worry that something might happen — like inflation or their lifespan increasing.

What are they doing to minimize the risk of running out of money?

More than half don’t have a car that’s newer than two years old. A lot own their homes outright. And they’re cutting back on extras, like travel and memberships.

I noticed that most of the successful retirees worked for large companies and in the public sector. They generally weren’t the self-employed ‘Millionaire Next Door’ types. What does that tell you?

That’s interesting because of what comes with being at those forms of employment. Things like matching retirement plan contributions are great because they push you into a style of saving. You lower your risk of not having a comfortable retirement by the sheer nature of working there.

Based on what the successful retirees said, what should people nearing retirement be doing so they can have successful retirements?

Number one: have an annual or monthly budget and stick to it. Number two: have a plan to retire. Number three: be disciplined as an investor. It’s very risky to make bets on the stock market or on real estate. If you’re disciplined, you can have a nice nest egg in retirement.

Richard Eisenberg is the Senior Web Editor of the Money & Security and Work & Purpose channels of Next Avenue and Managing Editor for the site. He is the author of How to Avoid a Mid-Life Financial Crisis and has been a personal finance editor at Money, Yahoo, Good Housekeeping, and CBS MoneyWatch.@richeis315